Poly(methylmethacrylate) particles, [PMMA], sterically stabilized, are typically prepared by suspension polymerization in a reaction medium such as an aliphatic hydrocarbon solvent, in which the monomer is soluble but in which the polymer is insoluble, and using free radical initiators such as benzoyl peroxide or azobisisobutyronitrile. The reaction medium also includes a steric stabilizer such as polyisobutylene or degraded butyl rubber. The reaction is allowed to proceed at elevated temperatures under an inert atmosphere. The process is capable of producing poly(methylmethacrylate) particles having diameters of the order of 0.3 um.
For some purposes, it would be desirable to be able to produce larger poly(methylmethacrylate) particles, or at least to produce batches of such particles including some particles of larger diameter. Presently available suspension polymerization processes, however, appear incapable of preparing such larger particles (see for example the chapter by D. J. Walbridge in the book entitled "Dispersion Polymerization in Organic Media", Barrett, K. E. J., ed., Wiley, New York, 1975 at p.87.